Micrometer-calipers



(NO Model.)

J. D. BISHOP.

I MIGROMETER GALIPERS. No. 389,734. Patented Sept. 18, 1888.

UNITED STATES PATENT OFFICE.

JAMES D. BISHOP, OF, SAN FRANCISCO, CALIFORNIA.

MICRO'METEFl-CALIPERS.

SPECIFICATION forming part of Letters Patent No. 389,734, datedSeptember 18, 1888.

Application filed April 2, 1888. Serial No. 269,337. (No model.)

To aZZ whom it may concern.-

Be it known that I, JAMES D. BISHOP, of the city and county of SanFrancisco, State of California, have invented an Improvement inMicro-Caliper Tools; and I hereby declare the following to be Et'fllll,clear, and exact description thereof.

Myinvention relates to certain improvements in devices for delicatemeasurements; and its object is to enable calipers for mechanical use tobe adjusted with absolute precision to the smallest variations ofmeasurement.

It consists of a standard steel or metal rule divided to any desiredscale, with a movable attachment sliding upon the scale,with grooves andset-screws facing right and left, the faces of the grooves being in thesame vertical plane, and a spring-piece bent at right angles withthesliding piece, to which it is attached, so that its edge may sinkinto any of the divisions of the rule and hold it'in place. To theopposite end of the rule is fixed another metal piece, having a movableportion with grooves corresponding to those on the first-named piece,and a micrometer or vernier screw, by which it may be advanced orreceded.

Referring-to the accompanying drawings for a more complete explanationof my invention, Figure 1 is a side elevation of the rule broken in themiddle and showing the attachments. Fig. 2 is a sectional view of thesame on the line a: or of Fig. 1, looking toward the left end of therule. Fig. 3 is a transverse section looking toward the right end. Fig.4c isa plan view.

A is a standard steel or metal rule divided to any desired scale, on theedge of which slides the movable attachment B. A groove, 0, is

out in one side of the rule parallel with its edge, and a tongue orfeather from the piece B extends into this groove or channel, so thatthe piece B may slide backward and forward upon the edge of the rule,but cannot move vertically or be taken off therefrom on account of thefeather or projection which extends into the slot. On the upper part,above the edge of the rule, are two deep slots or grooves, D D, facinghorizontally to-the right and left in opposite directions, and havingthe bottoms of the grooves in the same vertical plane. Ad-

justing-screws E E extend through the piece B, so that their points liewithin the grooves, as shown in Fig. 1, and they serve to adjust of therule.

for any wear, so as to keep the bottoms of the grooves in exactly thesame plane at all times.

Upon one side of the sliding piece B is a metal springpiece, G, one endof which is attached to thepiece B, and the other end, extending beyondthe piece, is bentat right angles and brought to a thin edge, whichrests upon the face of the rule, so as to drop into any one of thegraduated divisions cut on the rule; and by means of a thumb-screw, H,the edge of the spring may be clamped in any depression or division ofthe rule which may be desired, the movable piece B being firmly held atthe same time. By releasing the thumb-screw the spring lifts out of thedivision, and the piece B may then be shifted at will to any otherpoint. On the opposite end of't-he rule is fixed a metal piece, I. Ascrew-sleeve, M, is fixed to the metal piece I, and the screw L,extending parallel with'the face of the rule, turns in this sleeve. Thescrew has a head, forming a micrometer orvernierywhich may be divided toany degree of minuteness-as, for instance, the screw may have twentythreads to the inch and the head may have fifty divisionsso that amovement round its axis through the space of one division of the headwill advance the screw one one-thousandth of an inch. Any othersubdivisions may be madein like manner, as willbe obvious. This screw Lturns in a split screwsleeve, M, fixed to a sliding piece, N, theconstruction of which is similar to that ofthe piece B, and it is madeto advance or reccde, as desired, by the movement of the micrometer-headO, and its movements aremeasured from a line out on an independentpoint, P, fixed to the stationary piece I. The upper part of the movableportion N, which extends above the edge of the rule, has grooves D and Dupon opposite sides, these grooves corresponding in position to thesimilar grooves D D upon the part B, before described."

This tool is used as follows: Suppose it is de sired to set insidecalipers for boring a cylinder exactly eight inches. The micrometer-headis set to zero and the movable piece B is set free by loosening thespring G, so that it may slide along the scale until the spring fallsinto the notch representing the eight-inch division The screw H is thenturned so as to clamp the movable head B at that point. The calipers arethen brought to fit between the inner face of the groove D of the part Band the inner face of the groove D on the part N, which gives the exactsize.

The ends of the screws or the bottom of the grooves are slightly roundedin section, so as to permit of the more accurate use of the calipersupon them. If it is desired to turn a plunger to fit closely in theeight-inch cylinder, and it is estimated that the diameter must bethree-thousandths of an inch less than that of the cylinder, themicrometer screw is moved through three divisions, and the head-piece Nwill consequently be moved forward threethousandths of an inch. Thecalipers for outside measurement of the plunger are then brought to fitexactly in the grooves D of the parts N and B in the same manner as hasbeen described for adjusting the inside calipers, and this will give adiameter of eight inches less three-theusandths of an inch.

The micrometer-serew sleeve maybe kept tight at all times by tighteningup the screws Q, and the wear in the grooves D and D of the part B, andalso of the part N, if desired, may be compensated by advancing thescrews E, E, and E, as before described.

The tool, as above described, is mounted for i I l support on legs, or,preferably, is fastened to one face of a piece of angle-iron running itswhole length, the other face being perforated to receive screws forfixing the whole to a bed or table.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is v v 1. The rule A,with the sliding piece B,having the grooves or channels D D, and the holding-spring andlocking-screw, by which it is secured at any point upon the rule, incombination with the fixed piece at one end of the rule, the piece N,provided with grooves D and D, and the micrometer-screw, by which thispiece is advanced and receded, substantially as and for the purposeherein described.

2. The rule A, with the adjustable slides or pieces B and N, havinggrooves or channels D D, in combination'with the compensatingscrews E E,substantially as herein described.

In witness whereof I have hereunto set my hand.

JAMES D. BISHOP. \Vitnesses:

S. H. Noonsn, 1L 0. LEE.

